Long-term retrospective study of 52 horses with sinunasal cysts

The spectrum of clinical presentation, methods of diagnosis, management and prognosis in cases of sinunasal cysts (SNCs) requires more extensive study. Despite the extensive nature of SNCs, the prognosis for afflicted horses appears to have improved since earlier studies were conducted.

To evaluate prognosis and cosmetic outcome of surgical ablation in 52 cases of SNCs.

Fifty-two case records (1982-2005) of horses affected with SNCs were retrieved from the archives. Subject details, clinical signs, diagnostic techniques, surgical management and post surgical complications were extracted. Owners and referring veterinarians were contacted to assess the results of treatment.

There was no biphasic age distribution. The major presenting signs in descending order of frequency were facial swelling, mucopurulent nasal discharge, nasal airflow obstruction and abnormal respiratory noise. Common endoscopic findings included narrowed nasal meati, a cyst in the nasal cavity and a cyst visible caudal to the nasal septum viewed from the contralateral unaffected nasal meatus. Typical radiological signs included a discrete mass in the sinunasal region, a diffuse increase in opacity over the sinunasal region, free fluid lines, nasal septal deviation, expansion of the ventral conchal sinus and distortion of dental apices. Cyst extirpation using an osteoplastic flap provided a successful outcome. Forty-five of 48 horses showed complete resolution of clinical signs after subtotal or total extirpation of the cyst wall. Follow-up information was not available for the other 3 horses. Thirty-nine of 45 horses had a good to fair cosmetic appearance, judged to be good in 26 horses, fair in 13 and poor in 6. Results confirmed that the prognosis for full recovery has improved since a previous report of 15 cases.

Equine sinunasal cysts may arise in horses of any age; presenting signs should alert clinicians to their likely presence. A discrete well-circumscribed mass found during radiographic examination provides supporting evidence of a cyst. The vivid yellow, translucent, seromucoid fluid aspirated from cysts is characteristic of the condition.